Twin and multicore electric cable



Jan 29, 1929.

C. J. BEAVER TWIN AND MULTICORE ELECTRIC CABLE Filed Aug. 21, 1926 after unto Patented Jan. 29, 1929.

UNITED STATES PATENT OFFICE.

CHARLES JAMES BEAVER, OF BOWDON, ENGLAND, ASSIGNOR TO W. '1. GLOVEB AND COMIA NY LIMITED, OF MANCHESTER, ENGLAND.

TWIN AND MULTICORE ELECTRIC CABLE.

Application filed August 21, 1926, Serial No. 130,633, and in Great Britain September 4, 1925.

This invention is a new form of twin or multi-core cable.

' It is common to construct cables consisting of two or more spirally arranged conductors, each insulated by lappings of paper, fabrlc,

or other like material impregnated with insulating compound. enclosed inan outer circular covering, with the quasi-crescent shaped spaces between the conductors'and the outer covering, and (in the case of a cable containing more than two conductors) the central space between the conductors filled w1th a I padding composed of fibrous or hygroscopic material.

In one form of cable heretofore invogue there is laid up with, and interposed between, the conductors a stri or core of flexible material shaped to con orm to the shape of the inner surfaces of the conductors filling the central space between the conductors and projectin for a short distance into the quasicrescent s aped spaces, the purpose being toform a bed or comparatively wide area to receive each conductor, and so prevent the 1nsulated conductors from impinging together on a mere lineal contact when being laid up,

with the incidental risk of a compression,

and hence a weakening of the insulating at i the very parts where it is subjected to the greatest stress.

In cables of the type referred to, i. e., with the conductors insulated, and the spaces filled as aforesaid, diliiculty is experienced in preventing air or gases from being imprisoned in, or moisture penetrating into, the interstices in the fibrous or hygroscopic fillings,

and between the fillings'and the surfaces of the insulated conductors, and (in the case of a cable furnished with a central strip or more 40 as aforesaid) between the fillings and the surface of the strip, and this difiiculty is greater in reference to the crevices around and in the fillings in or near the, apices of the crescent shaped s aces, than in the arts thereof more remote high tension cables break downs occur consequent on the presence of air or gas or moisture in the crevicesreferred to. The object of this invention is to construct a cable composed of conductors insulated as aforesaid, in which the fillings are of such a nature, and the method of manufacture such, that the possibility of air gas or moisture being imom the centre 0 the cable, and in prisoned, or retained in such crevices as above referred to, is eliminated or reduced.

According to this invention the cable is made with a central strip or core such as described or referred to, and the remainder of the spaces is filled with a padding of vulcanized bitumen or the like, of the desired cross section shape to fill such spaces. I may preferably in order to exclude bubbles or films of air between the component parts, when laying them up together, coat the said stripswith a viscous material such as petroleum jelly, so that there shall be a surplus of such material to exude when the component parts converge. This process I may assist by compressing all the component parts together by a tight over-lapping of insulating fabric or any other solidif ing means which may form part of further apping of overall insulation in cases where the total-insulation is applied partly on the individual conductors and artly after they are laid up together. urther I may make the final .convergence of the parts in the laying up while submerged ininsulating oil or compound. The central strip or .core may be reinforced by a cord or strip of non-conducting material embedded therein, and each of the vulcanized bitumen strips, constituting the fillings, may

similarly be reinforced by a cord or strip embedded therein to enable the same to resist the strain incident to the process of laying up.

In the accompanying drawing an example of a cable made according to my invention is illustrated. a are the conductors, b are paper insulations, c is a strip of flexible material interposed between the conductors, and presenting to each insulated conductor a surface corresponding to the desired relative position of, and closely fittin against the surface ofv each insulated conductor, (1. are fillings made of strips of vulcanizedbitumen or the like, and e are cords or strips, of non conducting material embedded in such fill- Over all the described component parts is a layer f of fabric additional insulating lappings, or a lead sheathing.

The-cable is conveniently constructed by feeding in the strips of material 0, and the strips of fillings (1 into the required position in the course of laying up the insulated conductors.

With a cable constructed according'to this invention the elimination of air, gasesand moisture from the padding. itself is assured, and the elimination from the'crevices between such fillingis facilitated.

What I claim 1s:-

being shaped to conform to and contact with said core, conductors, and sheath.

2. An electric cable comprising a sheath,

a plurality of paper insulated conductors, of

circular cross section, a core of flexible material centrally arranged in the said sheath and separating said conductors from each other, said core ing formed .with'arcuate recesses conforming to and seating said conductors; fillin strips of nonhygroscopio lastio materia located in the several spaces hetweenthe core and each pair of conductors and betweenthe conductors and the sheath,

said strips being shaped to conform to and make contact with said core, conductors and sheath.

3. An electric cable, comprising a sheath,

a plurality of paper-insulated conductors, a

core of flexible material centrally arranged in the said sheath, and separtin the said conductors from each other, said core beingsha ed to conform to and contact with the sai conductors, and filling strips of vulcanized bitumen located in the spaces be tween the core and each pair of conductors contact with the sai and between the conductors andthe sheath,

said strips being sha ed to conform to and core, conductors and sheath. y s

4. An electric cable, comprising; heath, a plurality of paper-insulated conductors of circular cross section, a core f flexible ma terial centrally. arranged in the-said sheath and separating the said conductors fromeach other, said core being formed with arcuate recesses to seat said conductors, andfco nforms ing to and making contact therewith, and filling strips of vulcanized bitumen located in the spaces between the core a'nd'conductors and the sheath,lsaid strips being shaped to conform to and contact with, the said core, conductors'ahd sheath. 7

5. An electric cable, comprising a sheath, a plurality of paper-insulated conductors, a

Tcore of material, centrally arranged in said sheath and separating the said {conductors from each other, said core being shaped'to conform to and contact with the said conductors,

filling strips constituted of non hygrosco ic plastic material located in the 1 spaces etween the core each pair of conductors and the sheath and being'shaped to conform to and contact with the core and with such'co'ndoctors and the sheath, and anon-conduct 111g reenforc1ng cord having greater tensile strength than the core or filling'strips and embodied insaid core and in each of the said filling strips.

6. An electric cable as set forthin claim A l in combination with a coating of viscous material around 'each of the filling strips.

In witness whereof I have signed this specification.

. CHARLES JAMES BEAVER. 

